Isolation and characterization of margaric acid from an endophytic fungus of Zingiber officinale rhizome, its cytotoxicity and larvicidal activity against Anopheles gambiae

Endophytic fungi are source of promising biologically active metabolites for pharmaceutical and agricultural applications. This study is aimed at isolating and characterizing margaric acid from an endophytic fungus of Zingiber officinale and the determination of its larvicidal activity against Anopheles gambiae . An Arthroderma species was isolated from the rhizome of Zingiber officinale and identified based on the morphological characteristics of the colony and microscopically. The ethylacetate extract was obtained by liquid-liquid extraction of the fermented fungus in potato dextrose broth medium and it was subjected to column chromatography on silica gel, the isolated compound was characterized using 1-D NMR, 2-D NMR, IR and ESI-MS spectroscopic techniques. The 13 C NMR revealed the presence of seventeen carbon signals, from the 13 C DEPT 135 one methyl, and fifteen methylene carbon signals were observed from their chemical shifts. The FTIR showed a broad absorption band from 2500 cm − 1 to 3500 cm − 1 due to OH stretching of carboxylic acid and a strong peak was observed at 1707 cm − 1 which is attributed to carbonyl stretch. The electrospray ionization mass spectroscopy gave a pseudo molecular ion [M-H] − at m/z of 269.2581. The larvicidal activity of the isolated compound against third instar larvae of Anopheles gambiae at 24 h revealed significant activity with the highest percentage mortality of 70 at 1000 µg/ml and LC 50 value of 79.63. Brine shrimp lethality test of the compound showed an excellent cytotoxicity against brine shrimp larvae of Artemia salina with an LC 50 value of 3.010 µg/ml.